PDT may refer to:

• PHP Development Tools, an IDE plugin for the Eclipse platform
• PDT Standard Police Digital Trunking, China's police wireless communications standard
• Portable data terminal, an electronic device that is used to enter or retrieve data via wireless transmission

• Patient-delivered therapy
• Photodynamic therapy, treatment for cancer and wet age-related macular degeneration, involving a photosensitizer, light, and tissue oxygen
• Population doubling time, a number indicating cell growth in cell cultures
• Pancreaticoduodenal transplantation (see Pancreas transplantation)
• 1,3-Propanedithiol, an organosulfur compound

• Paramount Domestic Television, United States television series distributor, now CBS Television Distribution
• Piedmont Airlines (ICAO airline code), an American regional airline
• PDT Partners, a hedge fund company in New York City that was formerly the trading division of Morgan Stanley
• Pattern day trader (also Pattern day trading, PDT violation), a stock trader who frequently buys and sells a security within the same trading day

• Partido Democrático Trabalhista (Democratic Labour Party), a political party of Brazil
• Phi Delta Theta, an international fraternity

• Prague Dependency Treebank, a subset of the Czech National Corpus
• Plautdietsch (ISO 639-3 language code), a Low Prussian variety of East Low German, with Dutch influence

• Please Don't Tell, a cocktail bar in New York City
• Pacific Daylight Time (UTC−7), daylight saving time in western North America
• Eastern Oregon Regional Airport (IATA airport code), near Pendleton, Oregon
• Potentially dangerous taxpayer, an American taxpayer that has demonstrated a capacity for violence against the IRS
• Peter Dengate Thrush, New Zealand barrister
• psychedelic trip, a psychedelic experience